A flip-flop of the Earth's magnetic poles temporarily but significantly decreased the magnetic field's power more than 40,000 years ago, experts said. Such disaster could have caused a cascade of environmental crises on Earth, recent research indicates.
The researchers linked changes in temperature conditions, large mammal extinctions, and adjustments in human activity before and after the Laschamps excursion, a brief reversal of the magnetic poles that lasted fewer than a thousand years with the assistance of modern, reliable carbon dating collected from ancient tree fossils. The first research, the team notes in Science journal, explicitly relates a magnetic pole reversal to large-scale environmental shifts.
The Earth's protective magnetic field, which protects the world from a bombardment of charged particles streaming from the sun, will lose intensity during a reversal. Any scholars have also proposed that these flip-flops may be related to incidents of extinction.
Cosmic Hurricane
There is no defined position for the magnetic north pole, i.e., the direction a compass needle points to. Due to complex motions inside the Earth's core, it typically wobbles near the North Pole (the northern-most position of the Earth's axis) over time, much like the magnetic South Pole.
Often, for purposes that are not apparent, the magnetic poles' motions may be more dramatic. About 41,000-42,000 years ago, they absolutely switched locations.
Chris Turney, a researcher at UNSW Science and co-lead author of the report, told Phys.org the last time the magnetic poles turned was the Laschamps Excursion.
Scientific study has so far concentrated on modifications that existed when the magnetic poles were inverted. The magnetic field decreased to around 28% of its current power.
But the most exciting aspect was the lead-up to the turnaround, as the poles were migrating around Earth, results show.
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Prof. Turney noticed that the Earth's magnetic field fell to just 0-6 percent power during the Adams Event.
"We essentially had no magnetic field at all-our cosmic radiation shield was totally gone."
The paper indicates that certain other evolutionary mysteries, such as the disappearance of the Neanderthals and the apparent ordinary emergence of figurative art in caves around the world, might be clarified by the Adams Event.
Ancient Hints Unveiled
These observations come two years after the detection at Ngāwhā, Northland, of an incredibly significant ancient kauri tree.
During Laschamps, the huge tree was alive with a trunk stretching about two and a half meters.
UNSW's Dr. Jonathan Palmer, a tree-ring dating expert, said the wood of the Ngāwhā tree is so well protected that the bark is already attached, like other buried kauri logs.
Professor Alan Cooper, an Honorary Researcher at the Museum of South Australia, said that kauri trees are like the Rosetta Stone. Such a tree allows us to connect environmental change records worldwide in caves, ice cores and peat bogs.
Accelerant Like No Other
Although the magnetic poles sometimes drift, the north magnetic pole's recent fast migration through the Northern Hemisphere scares certain scientists.
"This speed-alongside the weakening of Earth's magnetic field by around nine percent in the past 170 years-could indicate an upcoming reversal," says Prof. Cooper.
"If a similar event happened today, the consequences would be huge for modern society. Incoming cosmic radiation would destroy our electric power grids and satellite networks."
Prof. Turney notes that the climate problem is devastating enough without tossing drastic solar shifts or a pole reversal into the mix.
Unparalleled climate shift accelerants, he notes, will be a gravitational pole reversal or drastic improvement in the Sun's operation.
"We urgently need to get carbon emissions down before such a random event happens again."
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